My 3rd Arduino Instrument is going to be "Cheapy GPS Nav". I decided since in this airplane I fly to just a few airports in the general area, I really do not need a database which covers airports a 1000 miles away. So I will make a limited database and allow for a few of the entries to be a "user" latitude and longitude in case I decide to go some place that is not in the database. With the Arduino, you have to be careful because the language is basically "C" and the use of libraries eats up memory fast (the cost of high level languages). The GPS module is on the back side of the assembly and an external antenna will be used. Maybe two or three weeks to finish.